Shotgun chamber with cutting edge



Jan. 20, 1.959 E. P. SIMMONS SHOTGUN CHAMBER WITH CUTTING EDGE Filed April 3, 1957 IN VEN TOR.

J m J F M m M This invention relates to new and useful improvements in shotguns, and has particular reference to shotguns of the automatic or pump types.

In guns of this type, the shell casing, after the gun is fired, is extracted from the chamber and ejected from the receiver of the gun through a suitable ejection opening formed in the receiver, this extraction and ejection being accomplished by a recoil operated mechanism in the case of an automatic gun, and by a manually operated mechanism in the case of a pump gun. In such guns, it has heretofore been possible to use ammunition of only one length, for example standard ammunition in which the shell casing is 2% inches long after the shell has been fired. On the other hand, a heavier ammunition is available in which the shell casing is 3 inches long after the shell has been fired. While many gunners would of course desire on occasion to use the heavier ammunition for the greater range and hitting power thereof, it has not been possible to use such heavy ammunition in guns built for standard ammunition, since both the length of the extraction movement and the length of the ejection opening in the gun receiver is proportioned for standard ammunition. While even the longer shell casing will be fully extracted from the chamber by the usual extraction mechanism, the casing is too long to be passed through the ejection opening, and ejectio-n therefore cannot occur. As a consequence, the heavier 3 inch ammunition has up to the present time required special guns. Attempts have been made to adapt standard guns for 3 inch ammunition by cutting away the receiver and related parts to lengthen the ejection opening, but this has been found hazardous since the gun is seriously weakened about the breech and may explode or be badly deformed when fired.

The principal object of the present invention is therefore the provision of a chamber member specially formed whereby permit the use of longer, heavier ammunition in guns otherwise constructed for shorter, lighter am-' munition. Generally, this object is accomplished by providing a chamber so constructed that it utilizes the pressure of the gases of explosion when the gun is fired to cut off the forward end portion of the shell casing, whereby the casing is reduced to a length equal to or less than the I th of the shell casing of the shorter ammunition for which the gun was originally intended. The shortened shell casing may then be extracted and ejected in a normal manner. The portion of the casing which was severed therefrom is discharged through the gun barrel with the remainder of the charge.

Another object is provision of a shotgun chamber of the character described which is adapted to receive either the shorter standard ammunition or the longer ammunition, interchangeably and without modification.

A further object is the provision of a shotgun chamber of the character described which may be formed either by a simple modification of pre-existing chambers, or; provided as original equipment on new guns.

Other objects are simplicity and economy of structure, etficiency and dependability of operation, and adaptability for use in many types of pre-existing shotguns.

With these objects in view, as well as other objects which will appear in the course of the specification,

reference will be had to the drawing, wherein:

Fig. i is a fragmentary side elevational view of a shotgun, with parts broken away and shown in section,.and showing a chamber modified to embody the prescent invention, said chamber having therein a shell ready for firing;

Fig. 2 is a fragmentary view similar to Fig. 1, showing the shell casing extended and the end portion thereof severed, after the shell has been fired;

Fig. 3 is a view similar to Fig. '2, but showing the chamber formed originally according to my invention, rather than by modification;

Fig. 4 is a view similar to Fig. 2, but showing the chamber before modification, and showing a shell of standard length therein; and

Fig. 5 is a sectional-view taken on line V-V of Fig. 1-.

Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies generally to a shotgun of the split-chamber type, including a hollow receiver iinto the forward end of which is threaded the gun barrel 6, the normal bore of said barrel being shown at 8. At its breech end portion, the barrel is provided with an enlarged bore 10 in which a tubular chamber member 12 is mounted for axial sliding movement. At its forward end, the diameter of the internal bore 14 corresponds to the normal bore 8 of the barrel. The diameter of the rearward portion 16 of the chamber bore is somewhat larger, being of a size to admit the shell 18 axially therein. Bore 16 may be very slightly tapered toward its forward end whereby to facilitate extraction of the shell from the chamber after it has been fired. Shell 18 comprises a metallic base 20 and a cylindrical casing 22 fixed in said base, said casing being formed usually of heavy waxed paper or cardboard. The forward end of the casing is folded inwardly to close the shell after it has been loaded, whereby the casing is shortened, but it is evident that when the shell is fired, the end portion of the casing will again be unfolded outwardly to its full length by the force ofthe explosion. The metallic base Zil of the shell is provided with an external rim 24 which engages a rearwardly facing shoulder 26 at the rearward end of chamber bore 16, thereby limiting the insertion of the shell into the chamber. A

breechblock 23 is disposed in the receiver 4-, and engages the base of the shell. y it will be understood that when the gun is fired, the breechblock is locked to the chamber, and that the force of recoil therefore drives the chamber, shell and breechbloca rearwardly. After a short movement, the breechblock is unlocked from the chamber, and continues rearwardly by recoil and inertia, while the chamber is halted and returned forwardly. During the continued rearward movement of the breechblock, an extractor 30 carried thereby and engaging shellrim 2d pulls the expended shell out of the chamber until it is aligned with an ejection opening 32 formed in gun receiver 4, and an ejector flips the shell laterally through said opening. The mechanism for performing these functions in itself forms no part of the presentinvention. I a

Referring now to Fig. 4, which showsachamber of Patented Jan. 20, 1959:

reduction of the diameter of the chamber from portion a 16 to portion 14 is accomplished by a conically bevelled wall 34, commonly known as the forcing cone. The shell 36 shown in Fig. 4 isof the standard length intended for use in the gun, the casing 38 of said shell being shown extended as after firing in solid lines, and the closed or unfired length thereof being indicated by dotted line 40. The shell when fired extends-approximately to the rearward end of the forcing cone as shown. It will be seen that the inner diameter of the casing is substantially equal to the forward bore 14 of the chamber, and to the diameter of the barrel bore 8. it will be understoodthat shell 36 in Fig. 4 is of such length that when extracted from the chamber as described above, the forward end'thereof will be moved behind the forward edge 42 of ejection opening 32 (see Fig. l) and that hence said shell may be ejected properly through said opening. However, a longer shell 18, say a 3 inch (open length) shell as compared to a standard 2% inch shell, will even before it is fired extend nearly to cone 34, and when fired mayextend substantially to the forward end of the cone, with the result that'when extracted from the chamber it still extends forwardly of ejection opening 32, and hence cannot be ejected therethrough. As previously mentioned, it is not practical to extend ejection opening 32 forwardly, since to do so dangerously weakens: the

structure. 7

In modifying the gun of Fig. 4 according to my invention, the forcing cone 34 is cut away to a cylindrical form equal in diameter to bore 16 of the chamber, and re placed by a cylindrical insert ring 44, as shown in Figs- 1, 2 and 5, the outer diameter of said ring corresponding to that of chamber bore 16, and the inner diameter there of corresponding to the diameter of chamber bore 14 and forming a rearward extension of said bore. The ring is silver-soldered or otherwise rigidly fixed in the chamber. The rearward end of the ring forms a shoulder 46 (see Fig. l), said shoulder being undercut for a purpose which will appear presently, and the inner edge of said shoulder forms a sharp cutting edge 48.

In operation, when the gun is fired, the paper shell casing 22 is unfolded and extended forwardly into ring 44, and expanded with great pressure by the gases of explosion, whereby the forward end portion 50 of the casing is severed by cutting edge 48. The severed end portion 50 is carried on through barrel 6 by the gases of explosion and/or the shot of the charge, while the shell casing is shortened to such an extent that it may be extracted and ejected in the same manner as though it had been of standard length. The undercutting of shoulder chamber has been tested thoroughly, and has been found? not'to increase the back pressure of the gun to any appree; ciable or objectionable extent. Since the radial width of? shoulder 46 is substantially equal to the wall thickness; of the shell casing, complete severance of said wall isv assured. At the same time, the casing wall itself serves: to protect the shoulder and cutting edge against the direct: erosive action of the gases of explosion, and against bat-- tering by the shot of the shell charge. Reduction of the bore diameter forwardly of the cutting edge provides that. the severed portion of the casing is maintained within a smaller diameter than the remainder of the casing, and directly in the path of the charge as it leaves the shell casing and starts through the barrel, thereby insuring that the severed portion of the casing will be discharged from the gun.

While I have shown and described a specific embodiment of my invention,'it will be apparent that many minor modifications of structure and operation could be made without departing from the spirit of the invention as defined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent is:

1. A shotgun chamber member for use with a shell having a foldable casing, the forward end portion of said casing being folded inwardly to close said shell and un folded outwardly to its full open length by the firing.

46 provides clearance which facilitates the cutting action of edge 48. Ring 44 may also be made of a specially hardened material, in order that cutting edge 48 will remain sharp over extended periods of use. It will be seen that the modification of the chamber as described in no way interferes with the use therein of the shorter standard ammunition shown in Fig. 4.

Fig. 3 shows a chamber which is unitary, the shoulder- 52 and cutting edge 54 shown therein corresponding in all respects to shoulder 46 and cutting edge 48 as shown in'Figs. 1 and 2. This type of chamber could be furnished either as a replacement part or as original equipment on new guns. It is evident also that while I have shown my invention applied to a split-chamber gun wherein the chamber 12 is separate from the barrel, the invention is equally applicable to automatic shotguns and pump guns wherein the chamber bore is formed in the barrel itself, so long as the ejection operation is carried out in the general way shown.

Thus it is apparent that a shotgun chamber having several advantages'has been produced. It permits the use of 3 inch (open length) ammunition in guns built to accommodate 2% inch (open length) ammunition, in a manner which is safe, efiicient and economical. The

thereof, said chamber member having a bore formed therein for receiving said shell with the base of said shell. at the rearward end of said chamber, said bore having a peripheral cutting edge formed concentrically therein of smaller internal diameter than the external diameter of' said casing, said cutting edge being spaced from the rearward end of saidchamber a distance substantially greater than the closed length of said shell but less than the open length of said shell, whereby when said shell is fired, the casing thereof will be extended forwardly past said cutting edge and expanded thereagainst by the gases of explosion, and the forward end portion of said casing will be severed by said cutting edge.

2. A shotgun chamber member as recited in claim 1 wherein the radial distance between said cutting edge and the wall of said bore is substantially equal to the thickness of said shell casing, whereby said casing will be completely severed, and whereby said shell casing will protect said cutting edge against direct erosive action by the gases of explosion.

3. A shotgun chamber member as recited in claim 1 wherein the bore thereof is of less diameter forwardly of said cutting edge than rearwardly thereof, the juncture between the reduced portion of said bore and the shellreceiving portion thereof being defined by a rearwardly facing shoulder, the inner edge of said shoulder constituting said cutting edge.

4. A shotgun chamber member as recited in claim 1 wherein the bore thereof is of less diameter forwardly of said cutting edge than rearwardly thereof, the juncture between the reduced portion of said bore and the shellreceiving portion thereof being defined by a rearwardly facing shoulder, the inner edge of said shoulder constituting said cutting edge, the axial length of said smaller portion of said bore being greater than the length of the portion of the casing severed by said cutting edge, whereby said severed end portion is retained within the reduced portion of the bore so as to be eifectively carried from the chamber with the charge from said shell. V

5. A shotgun chamber member as recited in claim 1 wherein the bore thereof is of less diameter forwardly of said cutting edge than rearwardly thereof, the juncture between the reduced portion of said bore and the shellreceiving portion thereof being defined by a rearwardly facing shoulder, the inner edge of said shoulder constituting said cutting edge, the radial width of said shoulder being substantially equal to the wall thickness of said shell casing whereby said casing will be completely sevwardly from the cutting edge thereof whereby to provide clearance for the cut edge of said shell casing.

References Cited in the file of this patent UNITED STATES PATENTS Pheatt Oct. 28, 1890 Febiger Aug. 15, 1905 Behar Oct. 16, 1923 Tomiska Aug. 6, 1929 Williams May 27, 1930 

